Sounds to me that your 360 is possibly faulty and there is no deleted folder or undelete option.
You could try a factory reset and try selecting the option to keep recordings, someone said this worked for them, if it doesn't then you might as well try the format disk option as you haven't got any recordings, and if the 360 loses everything again you will need to call Virgin on 150 from a Virgin phone, mobile or landline, or 0345 454 1111 from any other phone to report a fault or come back here and wait for one of the forum team to respond.
To factory reset go to Settings > System > Factory Reset.
It's only a partial system reset and not a complete factory reset. You are given 2 options,
Keep Recordings, that means you won't lose your recordings and any planned recordings or series links you've set up, you will have to sign into your apps such as iPlayer, Prime, Netflix and ITVX again, also Match frame rate and Standby power consumption will go back to their default settings if you have changed them.